This invention relates to an image forming apparatus, and more particularly to an image forming apparatus utilizing wet type development.
In a conventional image forming apparatus such as a copying machine, a latent image is formed on a photosensitive medium by applying light through an optical lens on the medium or irradiating a laser beam thereon to induce a voltage difference on the surface of the medium, and then is developed by adhering toners to the medium. In order to develop the latent image, a dry type development or a wet type development has been mainly adopted in the conventional image forming apparatus. As the wet type development, a conductive ink development method, a selective damping method, a cyst development method, a magnetic fluid method, etc. have been conventionally adopted.
In the conventional image forming apparatus utilizing the wet type development, an uniformly-charged recording medium, which has been exposed to light or supplied with an electrostatic field to form an electrostatic latent image, is supplied with wet type toners by an adhering device, and then is subjected to a heat treatment or the like to fix the toners to the recording medium and form an original image on the recording medium. Such a wet type image forming apparatus has the following disadvantages: an image of high resolution is more easily obtained than in a dry type image forming apparatus because the wet type toners are used in a state where they are resolved in a solvent, and a image is more clearly obtained when a solvent having low affinity to the recording medium is used because the substantially spherical toners are thickly adhered even to those fine regions of the recording medium where a minute latent image is formed. However, the solvent having low affinity to the recording medium ordinarily has a lower capability for preservation of the toners. That is, the toners would be denatured when they are preserved in the solvent for a long time.
Moreover, since a hardener and a vehicle are further mixed with a solution of the toners and the solvent, the mixed solution is difficult to due to the mixing of those materials even though the solvent has no bad effect on the preservation of the toners. As a result, an utilization efficiency of the charged toners and so on is lowered and a running cost becomes higher.